Contrast agent-free MR angiography with SSFP sequences

A magnetic resonance (MR) system that generates a non-contrast MR angiography image, comprising:

• an MR data acquisition unit adapted to receive an examination subject therein;
• a control unit configured to operate the MR data acquisition unit to acquire a first MR image of an examination region of the subject using a first steady state free precession (SSFP) imaging sequence comprising a plurality of repetition intervals, in which a gradient-induced phase development for unmoved and moved nuclear spins in the examination region is substantially completely rephased at an end of each repetition interval;
• said control unit also configured to operate the MR data acquisition unit with the examination subject therein to acquire a second MR image of the examination region using a second SSFP imaging sequence, also comprising a plurality of repetition intervals, in which the gradient-induced phase development for unmoved nuclear spins is also substantially completely rephased at an end of each repetition interval in the second imaging sequence, and in which a rest phase for moved nuclear spins exists at the end of each repetition interval of the second imaging sequence, wherein said second SSFP imaging sequence comprises a readout gradient and a rephasing gradient, and wherein said control unit is configured to operate said MR data acquisition unit to acquire said second MR image by causing said MR data acquisition unit to insert a time interval into said readout gradient between an end of a MR signal readout and said rephrasing gradient, before activation of said rephasing gradient, to generate said rest phase such that said rest phase destroys an SSFP signal of said moved nuclear spins;
• and
• a computerized processor supplied with said first MR image and said second MR image said processor being configured to subtract said second MR image from said first MR image to generate a non-contrast MR angiography image of the examination region.

A non-transitory computer-readable data storage medium encoded with programming instructions, said data storage medium being loaded into a computerized control and processing system of a magnetic resonance (MR) apparatus, which also comprises an MR data acquisition unit adapted to receive an examination subject therein, said programming instructions causing said computerized control and processing system to:

• operate an MR data acquisition unit with an examination subject therein to acquire a first MR image of an examination region of the subject using a first steady state free precession (SSFP) imaging sequence comprising a plurality of repetition intervals, in which a gradient-induced phase development for unmoved and moved nuclear spins in the examination region is substantially completely rephased at an end of each repetition interval;
• operate the MR data acquisition unit with the examination subject therein to acquire a second MR image of the examination region using a second SSFP imaging sequence, also comprising a plurality of repetition intervals, in which the gradient-induced phase development for unmoved nuclear spins is also substantially completely rephased at an end of each repetition interval in the second imaging sequence, and in which a rest phase for moved nuclear spins exists at the end of each repetition interval of the second imaging sequence, wherein said second SSFP imaging sequence comprises a readout gradient and a rephasing gradient, and wherein operation of said MR data acquisition unit to acquire said second MR image includes operation of said MR data acquisition unit to insert a time interval into said readout gradient between an end of a MR signal readout and said rephasing gradient, before activation of said rephasing gradient, to generate said rest phase such that said rest phase destroys an SSFP signal of said moved nuclear spins;
• and
• subtract said second MR image from said first MR image to generate a non-contrast MR angiography image of the examination region.